To be fair, the gene also repairs heart damage in Zebrafish
which is more than just "in mice".
I understand the reasons behind the meme "in mice",
but on the other hand dismissing valid progress because
humans reflexively insisting on exceptional snowflake status
is counterproductive.
Plus, the jumo from zebrafish to mice is a lot larger than the jump from mice to humans. If it still functions across that large of a jump then it's very likely it'll also work in humans.
Kind of makes you wonder what kind of biotechnology we could build if we didn't care about all that. There would be some pretty gnarly human suffering, but imagine if biological technology could progress at the same rate as electronics.
Morally abhorrent, of course, but there would be some benefits...
How easy are zebrafish to raise? What is their lifecycle? Can I raise millions of them in my basement or will I need to buy some warehouse? How long do they take? What do they eat? Any venture capitalists willing to fund my next business?
zebrafish are trivial, they are basically tropical fish that were repurposed for scientific research. temperature, ph, feeding, and cleaning the tank are the key steps.
Maintaining a population of zebrafish for scientific research is a bit more challenging; you need to maintain a continuous environment, adhere to a protocol, etc, to reduce all the variables that would your make your research results less reproducible.
zebrafish are imho one of the truly great model organisms- more interesting to work with and more convenient for many things. If I hadn't picked tardigrades for my microscopy/computer vision projects, I would have gone with zebrafish.
It's a common model organism in biology. One of the reasons is that it's easy to breed and keep in labs with fairly quick lifecycles. Raising millions of them is probably going to require a warehouse just like it would take to raise a million mice.